Generation of stabilized electrically-induced micro-plasma at the tip of multimaterial optical fibers

The aim of this work is to optimize the operation of a multimaterial optical fiber device to generate a stabilized electrically-induced micro-plasma. The fiber is composed of a polymer cladding with a central hole surrounded by two cylindrical metal electrodes. When a DC voltage of 1.2 kV is applied between electrodes, an air micro plasma is generated at the tip of the fiber. In order to stabilize the discharge, studies are focused on the modification of the electrical properties of the fiber tip by covering the electrodes with resistive layers. A comparison between two different layers (semi-conductive and semi-insulating) is shown. Characterizations were also performed for the fiber (head and length), and the plasma (imaging, spatial and temporal stability). The results show the effectiveness of the method to cover at least one of the electrodes by the semi-insulating layer to generate a permanent and stable discharge. In fact, this method allowed to increase considerably the lifetime of our technology and avoid the electric arcs leading to high instabilities. According to the Optical Emission Spectroscopy (OES), the species generated by the fiber-plasma device were identified.The combination of the characteristics of optical fibers with the properties of plasma allows diverse potential applications, such as gas detection in remote, confined, or harsh environments, high-level disinfection and sterilization of medical equipment or high-quality surface treatment (micrometric scale).